<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>焦点</title>
    <style>
        .iii {
            width: 175px;
            height: 35px;
            border: solid red 2.5px;
            box-shadow: 5px 5px 10px 10px black;
            margin: auto;
        }

        input {
            transition: opaticy .5s ease-in-out .5s;
        }

        input:hover {
            background-color: pink;
        }

        input:focus {
            background-color: blue;
        }
    </style>
</head>

<body>
    <div class="iii">
        <input type="text" placeholder="点我">
    </div>
</body>

</html>